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      Dissociated 24-Hour Patterns of Somatotropin and Prolactin in Fatal Familial Insomnia

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          To assess the changes in the 24-hour profiles of serum somatotropin and prolactin levels during total disruption of the sleep/wake cycle sustained over several months, we studied 2 subjects affected by fatal familial insomnia, a rare disease characterized by selective thalamic degeneration that causes chronic sleep loss. Under standardized conditions and polysomnographic control, the patients underwent repeated 24-hour study sessions covering the entire clinical course of the disease. Hormones were assayed at 30-min intervals. Four healthy volunteers were used as controls. A sleep/wake cycle was always absent in fatal familial insomnia. Serum somatotropin and prolactin concentrations never exceeded the normal range of variation. The nocturnal elevation of somatotropin disappeared simultaneously with sleep loss, whereas a significant 24-hour component of variations in serum prolactin levels was present for months after total disruption of the sleep/wake cycle, with normally placed nocturnal acrophases. Complete obliteration of the 24-hour component was achieved for prolactin only in the advanced stages, through a progressive decrease in 24-hour amplitude of variation. Selective and progressive degeneration of the mediodorsal and anterior ventral nuclei of the thalamus causes an early obliteration of the 24-hour rhythm of somatotropin and a later disappearance of circadian prolactin rhythmicity. The persistence of a significant circadian rhythm for months after total disruption of the sleep/wake cycle indicates that prolactin rhythmicity is not exclusively sleep-entrained.

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          Author and article information

          S. Karger AG
          09 April 2008
          : 61
          : 6
          : 731-737
          aDepartment of Internal Medicine University of Ferrara, bNeurological Institute, and cCentral Laboratory of S. Orsola Hospital, University of Bologna, Italy; dDivision of Neuropathology, Institute of Pathology, Case Western Reserve University, Cleveland, Ohio, USA
          126901 Neuroendocrinology 1995;61:731–737
          © 1995 S. Karger AG, Basel

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          Page count
          Pages: 7
          Prolactin and Lactation


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